Automatically variable camshaft



May 4,1937. E. c. GREGG 2,079,009

AUTOMATICALLY VARIABLE CAMSHAFT I Filed June 5, 1936 Jay? 6 reyy.

Patented May 4, 1937 UNITED STATES AUTOMATICALLY VARIABLE CAMSHAFT Earl C. Gregg, Enid, Okla, assignor of one-half to S. H. McEvoy, Enid, Okla.

Application June 3, 1936, Serial No. 83,366

4 Claims.

This invention relates to an improvement in the driving means of the cam shafts of internal combustion engines. These cam shafts are usually driven through a timing gear, and it is a primary object of the invention to provide very simple, compact and efiicient means through which the position of the cam shaft with respect to its driving gear will be automatically varied, in such fashion as to suit the particular engine speed at any given moment.

It is a well known fact that in order to secure efficient operation of an internal combustion engine, the timing of the spark must be advanced as the engine picks up speed. If the spark is set to occur before the crank passes dead center at the time of starting, the engine will kick back. Therefore, the spark must, at the time of starting, occur just after the crank passes dead center. However, if this later timing were maintained after the engine picked up speed, there would be serious waste of fuel and overheating of the engine, caused by the fact that with the late spark, the piston would be well down in the cylinder before the fuel could be ignited and expand and begin to exert its working force.

Therefore, the present invention aims to provide a cam shaft and driving timing gear for the same, capable of automatic adjustment through substantially 24 of travel. Thus, the

parts may be set to effect firing 12 before or 12 after top dead center of the crank and anything in between those extremes, according to the particular engine speed existing at any given moment, it being understood that at top speed, the firing is timed to occur 12 before top dead center. Correct timing renders it possible to use cheap grades of gasoline, results in lower oil consumption, keeps the valves in proper time with the ignition, makes a high-speed motor idle correctly, without cutting down the speed of the car, and promotes easy starting because the charge is'maintained at the highest efficiency.

One embodiment of the invention is illustrated in the accompanying drawing, wherein: Y

Figure l is an end elevation of the cam shaft with the timing gear thereon, and

Fig. 2 is a vertical sectional view through said gear and its associated parts.

Like numbers designate corresponding parts in both of the figures of the drawing.

Referring to the drawing, 5 designates the timing gear, and 6 the cam shaft. At its forward end, the cam shaft is secured to a disk I which has rotative mounting in a bearing bushing 8 of gear 5. Thus, the gear is mounted to rotate with respect to the cam shaft, but this rotation is'limited and is rendered automatically adjustable according to engine speed, through connections comprising a plurality of pins 9, which project forwardly from the face of the disk I and 5 enter slots I0, formed in one of the 'arms ll of bell crank levers l2.

These levers l2 are pivoted to rock upon pins or studs l3, and their outer arms, which are I somewhat longer than the arms ll, carry weights 10 M. Springs l5 are connected at one of their ends to the studs 13 and at their other ends are engaged over pins l6 of the long arms of the bell crank levers.

If the engine speed increases, the Weights I4 15 swing outwardly under the action of centrifugal force and against the tension of the springs l5. This results in moving the disk 1 with relation to the timing gear in the direction of the arrow a and to a degree proportionate to the increase 20 in speed. If the engine speed decreases, the springs act to return the cam shaft to its former position with respect to the timing gear.

From the foregoing description, it may be seen that the means proposed for accomplishing the desired result are simple, sturdy, compact, and are of a nature to insure smooth and effective operation through a long period of time. Other ways may suggest themselves, to those skilled in the art, of accomplishing the desired result. 30 Therefore, I wish it to be understood that the invention includes within its purview whatever changes fairly come within either the terms or the spirit of the appended claims.

Having described my invention, what I claim is: 35

1. The combination with a timing gear, of a disk upon which said timing gear is mounted for limited relative rotation, a cam shaft upon which the disk is fixed, the forward face of the disk and the forward face of the timing gear lying in 40 substantially the same vertical plane, a plurality of equidistantly spaced pins projecting forwardly from the face of said disk, a plurality of fixed pivots projecting forwardly from the face of the timing gear, equal in number to the number of 5 said pins, bell crank levers mounted upon said pivots and comprising long arms and shorter slotted arms, said slotted arms extending inward- 1y toward the cam shaft and overlapping the forward face of said disk and the pins of said 5 disk engaging in the slots of said arms, weights carried by the longer arms of said bell crank levers and spiral springs lying flat against the outer face of said bell crank levers, one end of said springs being attached to the pivots of the timing gear and the other ends of said springs being engaged with projections upon the longer arms of the bell crank levers.

2. The combination with a cam shaft and its timing gear, of a disk secured upon said cam shaft, a bearing for said disk in the timing gear through which the timing gear is mounted for limited rotation relative to saiddisk, pins projecting forwardly from the face of said disk, three equidistantly spaced weighted levers pivoted upon the face of the timing gear and having slots within which said pins engage, and springs re sisting movement of said levers under the influence of centrifugal force, as and for thepur-w poses set forth. a l

3. The combination with a carn shaft'and its timing gear, of a disk secured upon an end of the cam shaft, a plurality of equidistantly spaced pins projecting forwardly fromthe face of said disk, abearing-for the disk in the timing gear by which the timing gear is mounted forlimited rotative movement withrespect to,the disk, a plurality ,of fixed pivotsprojecting forwardly from the face of the timing gear, bell crank levers mounted upon said pivots, slots formed in one of the arms of each of the bell crank levers within which the pins of said disk engage, weights carried by the other arms of said bell crank levers, and springs engaged at one end with the pivot members of the timing gear and at their other ends with the bell crank levers in such position as to resist the movement of the bell crank levers under the action of centrifugal force.

4. The combination witha timing gear of a disk upon which said timing gear is mounted for limited relative rotation, a cam shaft by which the disk is carried, the forward face of the disk and the timing gearlying substantially in the same vertical plane, a plurality of equidistantly spaced vpinsprojecting forwardly from the face of said disk, a plurality of fixed pivots projecting forwardly from the face of the timing gear equal in number to the number of said pins, bell crank leversmounted upon said pivots and comprising long arms and shorter slotted arms, the said slotted arms overlapping the forward face of said disk and the pins of said disk engaging the slots of said levers, weights carried by the longer arms of said bell crank levers and springs resisting the movement of said weights outwardly under the action of centrifugal force.

EARL C. GREGG. 

